Technical Field
The present invention relates to a moving object detection apparatus that detects a moving object, such as a pedestrian, on the basis of picked up images.
Related Art
Techniques for detecting a moving object, such as a pedestrian, from the images picked by a camera or the like have been suggested. Some of such techniques make use of optical flows. Optical flows express the movement of an object in terms of vectors in the images obtained in time series by a camera or the like.
Specifically, in such a technique, feature points are extracted from an image and the positions of the feature points are specified in time-series images to obtain motion vectors of the individual feature points. In the present specification, a motion vector is referred to as “an optical flow”.
For example, a patent document JP-A-2009-157581 suggests a pedestrian detection apparatus that uses such optical flows for the detection of pedestrians. In this apparatus, a region in which optical flows have been detected is specified as a moving-object region. Then, a lower region having a size suitable for the size of the moving-body region is set below the moving-object region. It is then determined whether or not the lower region corresponds to a leg portion of a pedestrian, followed by specifying a whole-body region of the pedestrian.
However, if the region in which the optical flows have got together is immediately specified to be a moving-body region, noise included in the optical flows may induce erroneous detection of a moving body. Also, in determining whether or not a lower region corresponds to a leg portion, if the lower region is located behind a parked vehicle or the like, the lower region will not be necessarily determined to be a leg portion. Accordingly, if the leg portion of a pedestrian is invisible in an image (i.e., the leg portion is behind other objects), there is a concern that the pedestrian will not be necessarily detected, which may cause a dangerous situation.